Community Solar Power

June 27, 2008

A community in Canada has an unusual form of solar power that can provide over 90% of the annual heating and hot water needs for the homes, despite being situated in a cold Alberta location where winter temperatures can reach -33 degrees C (-27 F).

The Drake Landing Solar Community collects solar energy in a heat storage fluid through an array of solar panels on the roof of each home and covering all of the garages at the back of each home. The heated fluid is transferred to a neighborhood energy center, and then into the ground beneath an insulated layer, where the heat is stored in the earth.

Combined together, the 52 home community is able to collect and store enough energy from the sun during the summer that the ground storage temperatures reach 80 degrees C (176 F). This heat is sufficiently insulated beneath the ground that it can be drawn from throughout the winter to provide heat and hot water. The homes in the community are moderately sized, ranging from 1,492 to 1,664 square feet, and are insulated to a level 30% higher than the average home in Canada in order to keep the energy needs low enough to work with the system. The homes are also closely located to one another. This provides a more walkable neighborhood, as well as reducing the lengths that the fluid for the solar heating system needs to travel.

Entire Neighborhood Has Shared Solar Heating

The system works in part due to the scale of the project utilizing the combined capacity of the entire community. A similar system scaled down to a single family home version would not work as efficiently simply because too much heat would be lost. But the scale of a system for 52 households makes this a feasible project.

While the technology is similar to a ground source heat pump, which relies on a relatively stable, constant temperature of the ground, the Drake Landing Community is actually storing heat throughout the summer and then relying on that banked heat during the winter.

Solar heating is a more exciting prospect than solar generation of electricity because heating is a much larger percentage of a home’s total energy use (60% for space heating, 20% for water heating, and 20% for appliances, lights, and other electrical loads).